1. Field of Invention
The present invention relates to an optical element, and more particularly to an optical element having a holder and an optical lens combined with each other, and a manufacturing method thereof.
2. Related Art
In various different fields, an optical element having an optical lens fixed in a holder is widely used in optical communication devices, optical data reading devices, and other types of optical devices.
In the conventional manufacturing technique of the optical element, an optical lens and a holder are respectively formed. After a layer of glass paste having a low melting point is coated on an edge of the optical lens, the optical lens is placed in the holder. Then, the holder accommodating the optical lens is heated, such that the optical lens is combined with the holder, so as to finish manufacturing the optical element. In the process of manufacturing the optical element, the optical lens and the holder are combined after being respectively produced, and thus when the optical lens and the holder are combined, it is difficult to master the matching degree, such that gas tightness between the optical lens and the holder is poor, and the optical lens easily falls off from the holder.
In addition, the glass paste used to combine the optical lens with the holder during the manufacturing process is mostly the toxic material containing lead, which not only hurts the operators, but also impacts the environment, such that the manufacturing cost of the optical element is increased.
In order to solve the problem, recently, a method of forming optical element by utilizing a pressing mold is developed. An optical material is pressed in the holder by the pressing mold, and an outer surface of the optical material is adhered to an inner surface of the holder, so as to form the holder having the fixed optical lens. Meanwhile, in order to prevent the optical lens falling off from the holder, the inner surface of the holder is disposed as an arc face depressed from two ends of the holder to the middle part. Alternatively, a groove is opened on the inner surface, such that the optical lens is fixed in the holder.
Although the mold pressing manner may enhance the holding strength between the optical lens and the holder. However, the lateral side of the optical lens combined with the holder is a smooth plane, such that the gas tightness between the two may be poor. During the process of using the mold pressing, it is usually difficult to evaluate the deformation amount of the optical lens during molding because of the calculation error of the used volume of the optical material, so the precision of the optical lens is affected, and the yield and the performance of the finished product of the optical element cannot be effectively improved.
In the manner of opening the groove on the inner surface of the holder to fix the optical lens, the problem that it is difficult to calculate the deformation amount of the optical material is slightly relieved. However, in the manner of disposing the groove, when the optical material is molded to the optical lens, the flowing characteristic of the optical material is not considered. Therefore, the groove only has the function of fixing the optical lens in the holder, and the gas tightness is poor as well.